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How to build a Flyback transformer driver

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LAN_403

PlasmaPhysics

Wed Apr 14 2010, 08:33PM

Registered Member #2803 Joined: Wed Apr 14 2010, 07:47PM
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I need help with building a flyback transformer circit that pluses at kHz wave length for a plasma expirement I have the flyback transformer from a computer monitor now what? And no I'm not shocking random things with this it's for research.

hboy007

Wed Apr 14 2010, 09:12PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
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Posts: 374

No offence intended, but there are several threads about flyback drivers in this forum. A detailled discussion has been conducted here:

feel free to ask, but please take a few minutes to look through the related threads.
Oh, I almost missed it: Welcome to this forum!

ps. There are two basic things you can go for:
non-resonant mode (pulsed driving): the flyback actually works as a choke to generate fairly high voltage output. The power is within reasonable limits, often well within its specifications. Non-resonant drivers can be fixed or regulated, but the regulation feedback is not performed via PWM but rather via primary voltage variation.
The second thing would be resonant driving to create high resonant amplitudes within the flyback which now acts more like a transformer. The circuit is very popular, uses zero-voltage switching and works like the Royer oscillator but the MOSFET version became popular as Vladimiro Mazzilli's "Mazzilli driver" (in google mutilated vocabulary). You can find lots of videos of transformers hardly reaching the 20kV threshold but reaching output powers of 500-1000W during their short lifetime. If you're interested in plasma experiments, you'll want some beefy current to get higher ionisation states.

Another cool thing that in my opinion makes the non-resonant driver mode interesting is pulsed driving of low-inductance discharge experiments. You can get really interesting excitation states in low-density plasma using ceramic high voltage capacitors and thyratrons. You just need really high voltage (30kV+)

pps. you are talking about wavelength. I assume you mean the driving frequency. If you want a real RF generator, you won't get far with a DC flyback transformer (needless to say they have internal rectifiers)

cjk2

Wed Apr 14 2010, 10:30PM

Registered Member #51 Joined: Thu Feb 09 2006, 04:17AM
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"I need help with building a flyback transformer circit that pluses at kHz wave length for a plasma expirement I have the flyback transformer from a computer monitor now what? And no I'm not shocking random things with this it's for research."

The simplest driver you can build is a 2N3055 based one. Google for 2N3055 flyback driver.
A much better driver is the royer/ZVS based design. Google for ZVS flyback driver.
A 555 can be used to drive the base/gate of a transistor and that transistor can switch current through the primary of your flyback. This kind of driver will see large inductive spikes and needs to be clamped/snubbed, or use high voltage parts.

Google is your friend. Do all of the research you can, try to build a driver that you like, then post here if it doesn't work.

Here is the First result for a google search for "555 flyback driver"
http://tacashi.tripod.com/elctrncs/555sstc/555sstc.htm

moodymike

Thu Apr 15 2010, 10:41PM

Registered Member #2800 Joined: Mon Apr 12 2010, 03:09PM
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Here is single cap flyback if you are just learning and want to start off with something simple.

You may want to look into half or full wave circuits as well.
If you are working with plasma in a vacuum chamber, a simple
neon transformer would work well as a power supply for plasma.

cjk2

Thu Apr 15 2010, 10:57PM

Registered Member #51 Joined: Thu Feb 09 2006, 04:17AM
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Posts: 263

Try the ZVS driver. I would stay away from Sam's powerlabs. His site is about 8 years out of date and the 2N3055 drivers don't work well at all in the first place.

HV Enthusiast

Thu Apr 15 2010, 11:57PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

All you need is a simple half-bridge circuit driven by a variable oscillator circuit, such as a 555 timer set at 50% duty cycle.

moodymike

Fri Apr 16 2010, 12:25AM

Registered Member #2800 Joined: Mon Apr 12 2010, 03:09PM
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Sams is a little old, I just recommended it because it is a very simple circuit, with pictures on how he put it together, I though it would be an easy build for someone with little experience to get there feet wet with.
Can you give us a little more detail on what you are doing?
What are you planning on running with the flyback?
Plasma under vacuum can require very little to 50-60kv and more
It all depends on what you are trying to accomplish. It you are planning to
get past 30kv+ at some point, be aware and learn about the dangers of x-ray radiation,
Mike

PlasmaPhysics

Fri Apr 16 2010, 12:27AM

Registered Member #2803 Joined: Wed Apr 14 2010, 07:47PM
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Posts: 2

Thank you all for commenting,But I already have the equiptment needed for artificial plasma for non-thermal plasma applications. I now know its foolish and time comsomeing to make a power source out of a flyback transformer.

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